BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to a TTL automatic flash control camera capable of effecting
TTL multi-flash control.
Related Background Art
[0002] A camera system capable of effecting TTL automatic flash control has heretofore been
such that in a camera body, a light receiving element is disposed at a location facing
the whole or main portion of the surface of film and after a shutter interposed between
the surface of the film and the light receiving element is fully opened, a flash apparatus
is caused to start flashing and light created by the image of the object field being
reflected by the surface of the film is photoelectrically converted by the light receiving
element and a signal corresponding to the integrated amount of the quantity of light
is compared with a predetermined value, whereby the quantity of emitted light of the
flash apparatus is controlled so that predetermined brightness may be provided on
the surface of the film. The disadvantage of this system is that the detection area
of the object field is monistic and therefore various situations of the object field
cannot be coped with and the exposure of the main object the photographer desires
to photograph does not become proper. Some techniques for solving this problem have
been developed in recent years.
[0003] As one of them, U.S. Application Serial No. 560,745 (filed on July 31, 1990) based
on Japanese Patent Application No. 1-203735 proposes, the following automatic flash
control, the following system adopting the concept of multi-pattern photometry. A
plurality of photoelectric converters capable of dividing the object field into a
plurality of areas and metering these areas are disposed at locations facing the surface
of film and immediately before a focal plane shutter interposed between the surface
of the film and the plurality of photoelectric converters, a flash apparatus is caused
to effect preliminary flashing and light created by the object image by the flashlight
being reflected by the surface of a shutter curtain is caught by the plurality of
photoelectric converters and the outputs thereof severally integrated are detected
as the object field reflected light distributions of the respective areas by the flashing.
The detected object field reflected light distribution information of each area is
calculation-processed by predetermined multi-pattern algorithm, thereby determining
such a degree of weighting to each of the divided areas that optimum exposure is provided
to the main object. Subsequently, immediately after the shutter is opened, the flash
apparatus is caused to effect main flashing, and light reflected by the surface of
the film is caught a plurality of same photoelectric converters as said photoelectric
converters, and the weighting whose degree has been determined is effected on the
outputs thereof, and then the outputs are summed and integrated, and the flashing
of the flash apparatus is stopped at timing determined by the integrated value being
compared with a predetermined value, thus terminating the flash control of the main
flashing. That is, the quantity of emitted light is determined at timing for stopping
the flashing of the flash apparatus. The TTL flash control system of this camera system,
i.e., a TTL flash control system involving preliminary flashing, will hereinafter
be referred to as the "TTL multi-flash control". In contrast, a TTL flash control
system which does not involve preliminary flashing will hereinafter be referred to
as the "TLL ordinary flash control".
[0004] When it is desired that the technique of TTL multi-flash control disclosed in this
Japanese Patent Application No. 1-203735 be evolved in the actual camera system, both
of the camera body and the flash apparatus be endowed with predetermined new functions.
That is, it is necessary that the camera body have a photoelectric converter capable
of effecting split photometry, an output signal processing circuit, a sequence controller,
etc. and that the flash apparatus have a device for repetitively effecting preliminary
flashing and main flashing within a short time and controlling the quantity of emitted
light so as to limit the maximum quantity of emitted light in preliminary flashing
in order not to reduce the ability of main flashing very much.
[0005] However, the camera body and the flash apparatus which are endowed with the new functions
are in relality also connectable to those of the conventional type and in such a combination,
photographing can be accomplished only under the TTL ordinary flash control of the
conventional type.
[0006] Particularly, when flash photographing is to be effected with a flash apparatus of
the conventional type which is capable of TTL ordinary flash control mounted on a
camera body having the TTL multi-flash control function, the impression of a useless
possession is undeniable.
[0007] Also, when TTL multi-flash control photographing is possible, loss of some energy
is unavoidable even if a contrivance is made to limit the quantity of emitted light
during preliminary flashing as described above, and there is a demerit that the guide
number during actual photographing is reduced.
SUMMARY OF THE INVENTION
[0008] The present invention has been proposed to solve such a problem.
[0009] According to a first embodiment of the present invention, in a TTL automatic flash
control camera capable of effecting TTL multi-flash control, a first flash apparatus
(a built-in flash apparatus) is contained in the camera body and a second flash apparatus
(an accessory flash apparatus) is mountable on a connecting portion such as an accessory
shoe, and the first flash apparatus is caused to effect preliminary flashing to thereby
detect reflected light distribution information, whereafter the second flash apparatus
in its mounted state is caused to effect main flashing.
[0010] According to a second embodiment of the present invention, in a TTL automatic flash
control camera capable of effecting TTL multi-flash control, a first flash apparatus
(a built-in flash apparatus) is contained in the camera body and a second flash apparatus
(an accessory flash apparatus) is mountable on a connecting portion such as an accessory
shoe, and the presence or absence of the second flash apparatus mounted is detected,
and the first flash apparatus is caused to effect preliminary flashing to thereby
detect reflected light distribution information, whereafter if the presence of the
second flash apparatus mounted is detected, the second flash apparatus is caused to
effect main flashing, and if the absence of the second flash apparatus mounted is
detected, the first flash apparatus is caused to effect main flashing.
[0011] Thus, according to the present invention, in the TTL automatic flash control camera
of the first embodiment, if the accessory flash apparatus of the conventional type
capable of TTL ordinary flash control is mounted on the camera body, main flashing
is effected by the accessory flash apparatus in subsequence to the preliminary flashing
by the built-in flash apparatus and flash photographing under TTL multi-flash control
becomes possible.
[0012] Also, in the TTL automatic flash control camera of the second embodiment, when the
accessory flash apparatus is not mounted on the camera body, that is, even when the
accessory flash apparatus is not mounted depending on scene, preliminary flashing
and main flashing are effected on end by only the built-in flash apparatus, whereby
flash photographing under TTL multi-flash control becomes possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
Figure 1 is a cross-sectional view showing the optical arrangement of a photoelectric
converter in a TTL automatic flash control camera system according to the present
invention.
Figure 2 is a perspective view showing the structure of the photoelectric converter
and a condensing lens.
Figure 3 shows the optical positional relation among the opening area of the surface
of film, the photoelectric converter and the condensing lens as it is seen in the
direction of arrow A in Figure 1.
Figure 4 is a block circuit diagram showing a situation in which an embodiment of
the TTL automatic flash control camera according to the present invention is combined
with an accessory flash apparatus.
Figure 5 shows the interior of the light measurement and light adjustment circuit
shown in Figure 4.
Figure 6 is a timing chart of the release operation.
Figure 7 is a flow chart showing the operation of a microcomputer in the camera body.
Figure 8 is a timing chart of another embodiment.
Figure 9 is a flow chart of another embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] A TTL automatic flash control camera according to the present invention will hereinafter
be described in detail.
[0015] Figure 1 is a cross-sectional view for showing the optical arrangement of a photoelectric
converter in an embodiment of the present invention, and shows a state in which a
flash apparatus (accessory flash apparatus) 181 is mounted on a camera body 81. In
the camera body 81, inner rails 84a, 84b and a pressure plate 85 fix film 86 at a
position whereat a light beam passed through a photo-taking lens 82 in the state of
Figure 1 wherein a movable mirror 83 is retracted is imaged. The leading curtain 87
of a focal plane shutter lies immediately in front of the film 86 and intercepts light
in order not to permit the exposure of the film 86 during the other times than the
time of photographing. During exposure, i.e., when the leading curtain 87 of the shutter
is in its retracted state, the light beam L from an object is refracted by the photo-taking
lens 82 and imaged on the surface of the film 86, and part of it is reflected and
arrives at a condensing lens 92 and a photoelectric converter 91. During the other
time than exposure, i.e., when the leading curtain 87 of the shutter is at the position
of Figure 1, the light beam L from the object is refracted by the photo-taking lens
82 and substantially imaged on the surface of the leading curtain 87 of the shutter,
and part of it is reflected and also arrives at the condensing lens 92 and the photoelectric
converter 91. The reference numeral 89 designates a flash apparatus (built-in flash
apparatus) contained in the camera body 81, and the reference numeral 90 denotes the
trailing curtain of the focal plane shutter.
[0016] Figure 2 shows the structure of the photoelectric converter 91 and the condensing
lens 92. The photoelectric converter 91 is such that a circular light receiving area
PD11 and on the opposite sides thereof, light receiving areas PD21, PD31 and PD41,
PD51 of a rectangular shape cut away by an arc are disposed on the same plane. The
condensing lens 92 is an optical member having three lens portions 92a, 92b and 92c
corresponding to the three blocks of the light receiving areas.
[0017] Figure 3 shows the optical positional relation among the opening area 93 of the surface
of the film, the photoelectric converter 91 and the condensing lens 92 as it is seen
in the direction of arrow A in Figure 1. Assuming that the opening area 93 of the
surface of the film is divided into five areas, i.e., a central circular portion 93a
and four marginal rectangular portions 93b, 93c, 93d and 93e, the three central, left
and right blocks comprising the five light receiving areas of the photoelectric converter
shown in Figure 2 face the central portion, the left half and the right half, respectively,
of the opening portion of the surface of the film via the three lens portions of the
condensing lens, as indicated by a fine broken line, a dot-and-dash line and a rough
broken line, respectively, and cause them to be substantially imaged. Further, the
five light receiving areas PD11, PD21, PD31, PD41 and PD51 of the photoelectric converter
91 of Figure 2 are made coincident in shape with the areas 93a, 93b, 93c, 93d and
93e of the opening portion of the surface of the film shown in Figure 3 and therefore,
the photoelectric converter 91 is a photoelectric converter which divisionally meters
the brightnesses of the five areas.
[0018] Figure 4 is a block circuit diagram showing a situation in which an embodiment of
the TTL automatic flash control camera according to the present invention is combined
with an accessory flash apparatus.
[0019] This TTL automatic flash control camera system comprises a camera body 1 and a flash
apparatus (accessory flash apparatus) 101 which are electrically connectable together
through four contacts B1 - B4 and S1 - S4, and among these contacts, the contacts
B4 and S4 are GND connection terminals.
[0020] The flash apparatus 101 comprises a flashing portion 111 and a flash control circuit
112, which has a booster circuit, a main capacitor, a flashing control SCR, etc. and
controls the starting and stoppage of flashing of the flashing portion 111 in response
to a flashing start signal from the contact S2 and a flashing stop signal from the
contact S1. The contact S3 is normally connected to the GND connection terminal S4,
and an L-level signal produced at this contact S3 provides a signal for informing
the camera body 1 of the connection of the accessory flash apparatus 101.
[0021] The camera body 1 is comprised of a light measurement and light adjustment circuit
11 and a microcomputer 12 as main elements.
[0022] The internal circuit of the light measurement and light adjustment circuit 11 will
first be described with reference to Figure 5. PD11 - PD51 designate photodiodes as
the photoelectric converter shown in Figure 2 which is divided into five areas. These
photodiodes output photocurrents proportional to illumination. The photocurrent output
by the photodiode PD11 is converted into a voltage output logarithmically compressed
by an operational amplifier A11 subjected to the feedback of the photodiode PD11.
This output voltage is based on a reference voltage source E1 as a reference. Transistors
Q11 and Q12 use this voltage as the potential of their emitters and the input voltage
from a gain setting input terminal VG1 as the potential of their bases, and output
collector currents logarithmically expanded by a gain determined by the difference
between these potentials. The collector current of the transistor Q12 is inverted
by the current mirror circuit of transistors Q13 and Q14 and charges a capacitor C11.
The voltage stored in the capacitor C11 is output to an integrated voltage output
terminal V01 through a follower amplifier A12. FETQ15 receives the signal of an integration
control signal input terminal ITG and discharges all the charges stored in the capacitor
C11. These operations also hold true of the other four light measurement circuits
whose outputs are terminals V02 - V05. On the other hand, the collector currents of
five transistors Q11 - Q51 are summed and charge a capacitor C1. The voltage stored
in this capacitor C1 is compared with a reference voltage E2 by a comparator CP1,
and when the relation therebetween is reversed, the output of the comparator CP1 is
inverted from L to H, and an output terminal STOP changes from H to L. FETQ1 receives
a signal from the integration control signal input terminal ITG and discharges all
the charges stored in the capacitor C1.
[0023] The microcomputer 12 will now be described. The microcomputer 12 causes D/A converters
21 - 25 to set independent voltages by selection signals output from the five terminals
of output ports P07 - POB while outputting data from an 8-bit output port P0(8) to
the D/A converters 21 - 25 through a data bus 41. The output voltages of the D/A converters
21 - 25 are input to the gain setting input terminals VG1 - VG5, respectively, of
the light measurement and light adjustment circuit 11. The fine integrated voltage
output terminals V01 - V05 of the light measurement and light adjustment circuit 11
are connected to the A/D conversion input terminals AD1 - AD5, respectively, of the
microcomputer 12. The output port P01 is connected to the integration control signal
input terminal ITG. The reference numerals 35 and 36 designate mechanical switches
movable on the driving sequence of the camera. The switch 35 is a mirror up switch
adapted to be clsoed at a point of time whereat mirror up is completed, and the switch
36 is a synchro switch adapted to be closed at a point of time whereat the shutter
is fully opened. The reference numerals 37 and 38 denote switches operatively associated
with an operating member operated by the photographer. The switch 37 is a release
starting switch adapted to be closed when a shutter release button is depressed, and
the switch 38 is a flash control mode changeover switch for changing over the TTL
flash control method into a TTL multi-flash control directing mode for directing TTL
multi-flash control and a TTL ordinary flash control directing mode for directing
TTL ordinary flash control. The signals of the above-described four switches are connected
to the input ports P11 - P14, respectively, of the microcomputer 12 having pull-up
resistors. The reference numerals 31 and 32 designate magnets for holding the restraint
of a leading curtain 87 and a trailing curtain 89. Signals from the output ports P05
and P06 of the microcomputer 12 are given to these magnets, respectively, through
interfaces 33 and 34, whereby the driving of the magnets is controlled. The reference
numeral 51 denotes the flashing portion of a flash apparatus (built-in flash apparatus)
50 contained in the camera body 1, and the reference numeral 52 designates a flashing
control circuit. The flashing control circuit 52 has a booster circuit, a main capacitor,
a flashing control SCR, etc., and controls the starting and stoppage of the flashing
of the flashing portion 51 in response to a flashing start signal from the output
port P02 of the microcomputer 12 and a flashing stop signal from the STOP terminal
of the light measurement and light adjustment circuit 11. The STOP terminal of the
light measurement and light adjustment circuit 11 is connected to the flashing control
circuit 52 of the built-in flash apparatus 50 and is also connected to the flashing
control circuit 112 of the accessory flash apparatus 101 through a contact B1. Through
a contact B2, the flashing start signal to the accessory flash apparatus 101 is output
from the output port P03 of the microcomputer 12. A contact B3 is a contact for detecting
whether the accessory flash apparatus 101 is connected, and this contact is connected
to the input port P15 of the microcomputer 12.
[0024] The operation of the TTL automatic flash control camera system constructed as described
above will now be described with reference to a timing chart shown in Figure 6 and
a flow chart shown in Figure 7.
[0025] When a power source switch is first closed, the microcomputer 12 of the camera body
1 starts to execute the program. Thereby, at #1 shown in Figure 7, the microcomputer
12 discriminates the state of the switch 37, i.e., the release starting switch, and
if the switch 37 is OFF, the microcomputer repeats this and continues to wait for
the switch 37 to become ON, and when it is detected that the switch 37 is ON, advance
is made to #2 and so on, and the release operation is performed. In Figure 6, the
release starting switch 37 is closed at a point a shown in Figure 6(a), and this is
detected at #1 of the flow chart, and the release operation is started at a point
b.
[0026] At #2, the magnets 31 and 32 of the leading curtain and the trailing curtain, respectively,
are electrically energized, and at #3, a driver, not shown, is driven to start mirror
up (a point b shown in Figure 6(b)). At #4, the microcomputer continues to wait for
the switch 35, i.e., the mirror up switch 35 informing of the completion of mirror
up, to become ON, and when this switch becomes ON (a point c shown in Figure 6(c)),
the state of the switch 38 is discriminated at #5, and if this switch is ON, that
is, if the control method of TTL flash control set by the camera body 1 is the TTL
multi-flash control directing mode, advance is made to #6 and so on, and the object
field information detecting operation by preliminary flashing is started. That is,
at #6, D/A conversion is executed to give the same predetermined voltages to all of
the five gain setting voltage input terminals VG1 - VG5 of the light measurement and
light adjustment circuit 11 (a point d shown in Figures 6(h) - (1)). Then, advance
is made to #7, where for the light measurement and light adjustment circuit 11, ITG
as an integration start signal is rendered into L, and for the flashing control circuit
52 of the built-in flash apparatus 50, the output port P02 is rendered into L (a point
e shown in Figures 6(m) and (n)). Thus, the built-in flash apparatus 50 starts preliminary
flashing, and the quantity of emitted light falls as indicated by the flashing waveform
of a point e to a point f shown in Fgiure 6(o).
[0027] The photodiodes PD11 - PD51 of the light measurement and Igiht adjustment circuit
11 catch the reflected light from the object field and output photocurrents proportional
to the magnitude thereof. The circuit operation thereafter will now be described with
respect to a first channel related to the photodiode PD11. The photocurrent produced
in the photodiode PD11 is converted into a voltage output logarithmically compressed
by the operational amplifier A11 and the feedback diode D11, and is again converted
into a current output logarithmically expanded by the transistors 011 and Q12 whose
emitters are at the potential of said logarithmically compressed voltage output and
whose bases are at the potential of the gain setting voltage input VG1, and after
all, the collector currents of the transistors Q11 and Q12 are amplified by a gain
determined by the potential of VG1 while keeping a proportional relation with the
photocurrent, and exhibit an output current waveform similar to the flashing waveform
shown in Figure 6(o). The collector current of the transistor Q12 is converted into
a source current of the same value by the current mirror circuit comprising transistors
Q13 and Q14, and this current charges the capacitor C11 liberated from its short-circuited
condition by the falling of the ITG signal. The charging voltage of the capacitor
C11 is converted into a voltage output of low impedance by a buffer amplifier A12
and is put out from the output terminal V01. This output voltage rises as indicated
by the waveform of V01 from a point e to a point f shown in Figure 6(t). This is the
photocurrent amplified by a predetermined gain and then integrated, and represents
it in the form of a voltage of GND standard. With regard to second and subsequent
channels, the quantity of reflected light from the object field only varies independently
and the circuit operation itself is similar to what has been described above. Since
the same voltages are given in advance to VG1 - VG5 and the gain is made constant,
the transistors Q11 - Q51 put out electric currents resulting from the photocurrent
being amplified by the same gain. These are parallel-connected and therefore, an electric
current resulting from the sum total of the photocurrents of the channels being amplified
is stored in the capacitor C1. The terminal voltage of this capacitor C1 varies as
indicated by the waveform of the C1 integrated voltage shown in Figure 6(r), and when
this voltage becomes lower than the reference voltage E2, the comparator CP1 inverts
the output and the terminal STOP changes from H to L, and this signal is transmitted
to the flashing control circuit 52 of the built-in flash apparatus 50 (a point f shown
in Figure 6(s)). Thereby, the built-in flash apparatus 50 stops flashing. Accordingly,
the photocurrents produced by the photodiodes PD11 - PD51 also become null, and the
charging to the integrating capacitors C11 - C51 is stopped and the voltages of the
output terminals VOI - V05 are fixed.
[0028] Next, in the flow chart of Figure 7, at #8, waiting is effected for a predetermined
time with the maximum value of the time until the termination of the preliminary flashing
control operation taken into account, in order to secure the time for which the light
measurement and light adjustment circuit 11 performs the above-described operation.
At #9, the integrated voltages of the output terminals V01 - V05, by preliminary flashing,
corresponding to the divided areas of the object field are A/D-converted by an A/D
converter contained in the microcomputer, and at #10, the result of the A/D conversion
is passed through a predetermined multi-pattern calculation algorithm and the degree
of weighting to the divided areas during main flashing for photographing is determined.
What is disclosed, for example, in the aforementioned U.S. Application Serial No.
560,745 would be supposed as the substance of this multi-pattern calculation algorithm,
but it is not directly related to the gist of the present invention and therefore
need not be described herein. When the multi-pattern calculation is terminated, at
#11, ITG and port P02 are both restored to H (a point g shown in Figures 6(m) and
(n)), and the integration capacitors C1 and C11 - C51 in the light measurement and
light adjustment circuit 11 are caused to discharge and preparations are made for
the next main flashing operation. At #12, the D/A conversion of five channels is executed
to give gain setting voltages for the respective channels to the terminals VG1 - VG5
after reflecting the degree of weighting to the divided areas determined at #10, and
taking into account the adjustment of the gain to the film speed (a point h shown
in Figures 6(h) - (1)). Thereby, setting is effected such that an electric current
of enhanced amplification factor is integrated with regard to a divided area higher
in weighting.
[0029] On the other hand, if at #5, the control method of the TTL flash control of the camera
body 1 is selected to the TTL ordinary flash control directing mode, the preliminary
flashing operation by #6 - #12 is not effected but skip is made to #13, where the
D/A conversion of the five channels is executed to give the terminals VG1 - VG5 a
predetermined gain setting voltage including only the film speed so that uniform weighting
may be provided with regard to the respective divided areas. Speaking in the timing
chart shown in Figure 6, the variation in the signal waveform up to immediately before
a point d to a point h shown in Figures 6(h) - (1) becomes null, and the operation
of the point h is performed at the point of time of the point d. Accordingly, the
falling pulse from the point e to the point g of ITG and port P02 shown in Figures
6(m) and (n) is not put out in this case and the preliminary flashing by the built-in
flash apparatus 50 is not effected. Thus, TTL ordinary flash control is effected in
such a form that uniform light measurement (average light measurement) is done with
respect to the entire area of the surface of the film.
[0030] In the preparations hitherto, at #14, the magnet 31 of the leading curtain is electrically
deenergized to start the actual shutter release operation (a point i shown in Figure
6(d)). Thus, the leading curtain 87 starts its movement. At #15, the closing of the
switch 36 after the shutter is fully opened is waited for, and when this switch is
clsoed (a point j shown in Figure 6(g)), the level of a contact B3 is immediately
discriminated at #16 and if the level is L, that is, if the accessory flash apparatus
101 is detected as "being mounted", at #17, ITG and a contact B2 are both rendered
into L and the starting of main flashing is commanded to the accessory flash apparatus
101 and the starting of the integration in the light measurement and light adjustment
circuit 11 is permitted. If at #16, the contact B3 is at H, that is, if the accessory
flash apparatus 101 is detected as "being not mounted", at #18, ITG and port P02 are
both rendered into L and the starting of main flashing is commanded to the built-in
flash apparatus 50, and also the starting of the integration in the light measurement
and light adjustment circuit 11 is permitted. The timing chart of Figure 6 is shown
with respect to a case where the accessory flash apparatus 101 is mounted, and the
accessory flash apparatus 101 effects flashing as indicated by the flashing waveform
of Figure 6(q). Thereby, in the light measurement and light adjustment circuit 11,
the integration capacitor C1 is charged with the sum total of the expanded currents
of the transistors Q11 - Q51 now including weighting. When this exceeds the predetermined
reference voltage E2, the STOP terminal changes from H to L, and this signal is given
to the accessory flash apparatus 101 via contacts B1 to S1. Thus, the accessory flash
apparatus 101 stops flashing (a point k shown in Figure 6(q)). At this point of time,
exposure for photographing effected with the accessory flash apparatus 101 as a light
source is terminated. The program of the microcomputer 12 measures the time after
the magnet 31 of the leading curtain is deenergized at #14, and deenergizes the magnet
32 of the trailing curtain at #20 at a point of time whereat the set shutter time
has elapsed (a point 1 shown in Figure 6(e)). Also, on the spot, at #21, all the terminals
of ITG, the contact B2 and the port P02 are restored to H, and preparations are made
for the release operation for the next frame. Thereafter, when a shutter charge driver
and a mirror down driver, not shown, are driven, the switch concerned in each sequence
restores its original OFF state at points m and n shown in Figure 6(c). Thus, the
operation during the shutter release is terminated.
[0031] Another embodiment will now be described with reference to Figures 8 and 9. In this
embodiment, preliminary flashing is effected by the accessory flash apparatus mounted
on the camera body, and subsequently main flashing is effected by the built-in flash
apparatus contained in the camera body, whereby flash photographing under TTL multi-flash
control is accomplished.
[0032] This embodiment is identical in most constructions to the previously described embodiment,
but differs in the exchange of some signals from the latter embodiment. Accordingly,
the constructions of portions differing from those of the previously described embodiment
will hereinafter be described.
[0033] The operation of this TTL automatic flash control camera system will now be described
with reference to the timing chart of Figure 8 and the flow chart of Figure 9.
[0034] When the power source switch is first closed, the microcomputer 12 of the camera
body 1 starts to execute the program. It executes #1 - #6 of Figure 9 (as in Figure
6). Thereafter, advance is made to #70, where for the light measurement and light
adjustment circuit 11, ITG is rendered into L as an integration starting signal and
for the flashing control circuit 112 of the accessory flash apparatus 101, the contact
B2 is rendered into L (a point e shown in Figures 8(m) and (p)). Thus, the accessory
flash apparatus 101 starts preliminary flashing, and flashes as indicated by the flash
waveform from a point e to a point f shown in Figure 8(q). Thereafter, the light measurement
and light adjustment circuit 11 performs an operation similar to that in the previously
described embodiment.
[0035] At #15, the closing of the switch 36 is waited for after the shutter is fully opened,
and when this switch is closed (a point j shown in Figure 8(g)), at #170, ITG and
the contact P02 are both immediately rendered into L and the starting of main flashing
is commanded to the built-in flash apparatus 50. Then, the starting of the integration
in the light measurement and light adjustment circuit 11 is permitted. Thereafter,
an operation similar to that in the previously described embodiment is performed.
[0036] As described above, in the first embodiment of the present invention, if an accessory
flash apparatus of the conventional type capable of effecting TTL ordinary flash control
is mounted on the camera body, main flashing is effected by the accessory flash apparatus
in subsequence to the preliminary flashing by a built-in flash apparatus and flash
photographing under TTL multi-flash control becomes possible. That is, simply by a
built-in flash apparatus being provided in a camera body endowed with the TTL multi-flash
control function, any of many flash apparatuses capable of effecting TTL ordinary
flash control which are commercially available can become a member of a TTL multi-flash
control camera system. Also, by making the built-in flash apparatus have charge of
preliminary flashing, the fear of reducing the guide number during main flashing is
eliminated.
[0037] Also, in the second embodiment of the present invention, if an accessory flash apparatus
is not mounted on the camera body, that is, even if an accessory flash apparatus is
not mounted depending on scene, preliminary flashing and main flashing may be effected
on end by only a built-in flash apparatus, whereby flash photographing under TTL multi-flash
control becomes possible. That is, as long as an object at a relatively short distance
is to be photographed, preliminary flashing and main flashing may be effected on end
by only the built-in flash apparatus without an accessory flash apparatus being mounted,
whereby TTL multi-flash control photographing becomes possible and the range of flash
photographing becomes wider and wider.